The purpose of this proposal is to elucidate cellular mechanisms involved in the IgE antibody response and to find immunological manipulations for the suppression of IgE antibody formation. Previous studies have shown that the mechanisms for IgE antibody response are similar to those of IgE antibody response against T-dependent antigens, however, mechanisms for the distribution of antibodies among different immunoglobulin classes are unknown. Based on our previous findings, two experimental models will be employed in the present proposal; one is the IgG formation in the rat infected with Nippostrogylus brasiliensis and another system is the IgE antibody response in high responder mice. Using the rat system, the origin and mechanisms for the development of IgE-bearing B lymphocytes will be investigated. In the mouse system, we shall study 1. role of the helper and suppressor T cells in the development of IgE-B memory cells and 2. role of antigen-specific suppressor T cells (and non-specific suppressor cells) in the dissociation between IgE and IgG antibody responses. Adoptive transfer technique will be utilized in the studies. In view of previous findings which indicate that suppressor T cells actually regulate IgE antibody response, attempts will be made to find a more effective and selective way to generate suppressor T cells. Mechanisms for suppression of IgE antibody response by suppressor T cells will be studied using "functionally pure" suppressor T cells. In connection with this subject, possible relationship between suppressor (or helper) T cells and cytolytic effector T cells will be studied in both allogeneic and "modified self" systems.